The present invention relates to a method and apparatus for filtering liquids and more particularly to a unique and novel method for separating undesirable contaminants from a liquid through a liquid pervious filter support having a filter medium disposed partially therearound, the filter support being under a negative pressure as filtered liquid is removed internally therefrom.
Liquid filtration through an endless filter media support and traveling filter media sheet in contact therewith is generally known in the liquid filtration art, attention being directed to U.S. Pat. No. 2,720,973, issued to M. J. Gross on Oct. 18, 1955, and to U.S. Pat. No. 2,720,973, issued to L. L. Fowler, also issued on Oct. 18, 1955, both of which teach a combined magnetic separator and liquid filter arrangement of the drum type. Further attention is directed to U.S. Pat. No. 3,276,595, issued to J. Houpillart on Oct. 4, 1966 and to No. 3,836,006, issued to Steven S. Davis on Sept. 17, 1974, both of which teach rotatable drum liquid filter combined with contacting filter cloth, the Houpillart patent further teaching a pair of spaced endless belts registering with the marginal edges of the filter cloth to seal such edges against the drum, such a feature being further shown in U.S. Pat. No. 3,807,569, issued to R. L. Shaffer on Apr. 30, 1974. In addition, attention is directed to the rotatable drum filters in U.S. Pat. No. 4,428,838, issued to J. L. Creps, et al., on Jan. 31, 1984; No. 4,467,633, issued to S. N. McEwen, et al., on Aug. 28, 1984; No. 4,507,061, issued to S. N. McEwen, et al., on Mar. 26, 1985; and No. Re. 32,165, issued to J. L. Creps, et al., on May 6, 1986. Finally, attention is directed to U.S. Pat. No. 3,087,620, issued to G. Hirs on Apr. 30, 1963; to U.S. Pat. No. 3,127,256, issued to R. J. Boylan on Mar. 31, 1964; to U.S. Pat. No. 3,690,466, issued to W. J. Lee on Sept. 12, 1972; to U.S. Pat. No. 4,137,169, issued to A. M. El-Hindi on Jan. 30, 1979; and to U.S. Pat. No. 4,186,090, issued to J. Van Oosten on Jan. 29, 1980. All five of these later mentioned patents teach endless or continuous filter web arrangements supportable on foraminous screens in a flat bed arrangement with four of such five patents each including a liquid filter tank to accommodate liquid from the contacting filter web and endless filter support.
For the most part, the numerous structures of the prior art have been comparatively complex in manufacture, assembly and operation, requiring frequent, on-off, vacuum operations through only partially liquid submerged compartmentalized sections with a submergence usually of less than forty (40) percent, necessitating comparatively limited negative pressure levels with the filter media covering well under one half of the filter support face area. The present invention, recognizing the numerous limitations of past liquid filtration apparatus including continuously fed filter media contacting either an endless rotatable drum filter support or a longitudinally extending foraminous endless belt filter support submerged in a liquid tank, provides a unique and novel filter apparatus which includes both an endless filter support and continuously fed filter media contacting such filter support in sealed relation therewith with the filter support in either fully liquid submerged or partially liquid submerged condition with the contacting filter media covering as much as ninety (90) percent of the area of the porous portion of the filter support. In accordance with the novel features of the present invention, maximum contact can be made between the filter media and filter support with liquid filtration being conducted efficiently at comparatively high negative pressures with a minimum of filtration interruption. Further, the present invention provides a novel arrangement for simultaneously indexing the filter support and filter cloth feed during efficient removal of filtered liquids internally from the filter support and, at the same time, allowing efficient removal or stripping of a majority of the contaminants collected on the filter media prior to removal of the media from contact with the filter support. In addition, the present invention allows for modular removal and reinsertion into a liquid treating zone of the entire filtration structure including supply and take-up rolls, filter support and guide assembly.
Various other features of the present invention will become apparent to one skilled in the art upon reading the disclosure set forth herein.